For retrofits, the retrofit capacity is tied to the capacity of the original generator so that retrofit capacity + original capacity + retrofit penalty is less than pcap max. And separately, the original generator's capacity has to be nonincreasing every year meaning that if the model endogenously retires a coal unit, that unit can't come back online - its capacity is locked in at zero.
The retrofit mod creates a separate row/variable for each year of potential retrofit, and these rows are linked to each other and the original pcap max (i.e retrofit_y1 + retrofit_y2 ... retrofit_yn + original < pcap max). Therefore, a unit can retrofit years after the original retired as long as the sum of the retrofit capacity across all years and the remaining original capacity is less than pcap max.
There would be some basis in reality for this behavior - a coal generator likely will have to shut down for some amount of time while it undergoes the retrofit. However, in the edf-co project, units were retrofitting 6 years after coal retirement.
Fix: the retrofit ceiling has to depend on the original generator's actual capacity trajectory rather than the static pcap max so that once a generator has been driven to zero, all retrofits should be fixed to zero for that year and all subsequent years.
For retrofits, the retrofit capacity is tied to the capacity of the original generator so that retrofit capacity + original capacity + retrofit penalty is less than pcap max. And separately, the original generator's capacity has to be nonincreasing every year meaning that if the model endogenously retires a coal unit, that unit can't come back online - its capacity is locked in at zero.
The retrofit mod creates a separate row/variable for each year of potential retrofit, and these rows are linked to each other and the original pcap max (i.e retrofit_y1 + retrofit_y2 ... retrofit_yn + original < pcap max). Therefore, a unit can retrofit years after the original retired as long as the sum of the retrofit capacity across all years and the remaining original capacity is less than pcap max.
There would be some basis in reality for this behavior - a coal generator likely will have to shut down for some amount of time while it undergoes the retrofit. However, in the edf-co project, units were retrofitting 6 years after coal retirement.
Fix: the retrofit ceiling has to depend on the original generator's actual capacity trajectory rather than the static pcap max so that once a generator has been driven to zero, all retrofits should be fixed to zero for that year and all subsequent years.